lyngby_full2mask

 lyngby_full2mask     - Convert indices from Full volume to ROI volume

       function indexInMask = lyngby_full2mask(indexInFull);

       Input:  indexInFull   Scalar index in Full Volume or 3 element
                             vector with x,y,z index in full volume

       Output: indexInMask   Scalar index in ROI volume. An empty
                             matrix is returned if the index is not
                             in the ROI or is not within the VOXEL_MASK

       See also: lyngby_mask2full, lyngby_index2vmask,
                 lyngby_vmask2index, lyngby_roi